On 11/1/2013 6:24 PM, KM5VI wrote:
This is a bit different. We were pouring my shop floor which is high
strength (and lots of fiber). It was taking several truck loads and at
the truck load price I did the base and guy anchors with the stuff as
well. Since then, the price of concrete has skyrocketed. While I
haven't checked recently it was over 3 times what I paid and I have no
reason to believe it dropped any. Steel has come down some, but not a
lot. Why concrete went so high I don't know.
At any rate mine was a guyed tower so the base receives no where near
the stress of a self supporting tower base.This was one of the old
installations where the short section is set in the concrete, in firm
soil. For the less than two yards of high strength concrete we didn't
even use rerod in the base which only required light sprinkling as it
remained moist. At he end of the first week I had two sections up, but
no more for a month. The guy anchors had mo load for about 6 weeks and
the tower went up slowly from there.
I'm planning on waiting a month with the LM470 and it gets a rebar cage
that is the same as the factory one. That is, when I can get back out
there and finish it.
This time of year, even having to sprinkle it is rare around here, but
you do need to cover it some nights to keep the frost away.
73
Roger (K8RI).
Concrete cures very quickly at first and slows as time progresses - most
mixes will develop about 2/3rds (or more) of their 28-day strength within
the first 7 days after placement. I have erected crank-up towers 10-14 days
out (without wind) more than once but left them retracted just in case the
winds came up unexpectedly. Peak stresses don't develop in the foundation
if peak loads are not present... the dead weight loading of the tower is
generally negligible compared to the live wind loading.
KM5VI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Rex
Turvin
Sent: Friday, November 01, 2013 1:49 PM
To: towertalk
Subject: [TowerTalk] concrete
I'm going to be pouring concrete for my base foundation and 3 guy anchors
next week. Does anyone know how long I need to let it cure beforeI start
erecting the tower?
73 NR6M
ex: KF7NMD
Sincerely,
Rex Turvin
www.nr6m.com
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